Numbers 1:47-50

47But the Levites were not numbered among them by their fathers’ tribe;

48for the Lord had spoken to Moses, saying:

49“Only the tribe of Levi you shall not number, nor take a census of them among the children of Israel;

50but you shall appoint the Levites over the tabernacle of the Testimony, over all its furnishings, and over all things that belong to it; they shall carry the tabernacle and all its furnishings; they shall attend to it and camp around the tabernacle.